mkfs.xfs: cannot open /dev/[device]: Device or resource busy

If you hit this error trying to format a partition after you have installed a new disk in your server:

~# mkfs -t xfs -f -i size=2048 /dev/sdav2
mkfs.xfs: cannot open /dev/sdav2: Device or resource busy

Maybe you have multipath enabled and the new device has been detected. Run this command to see if multipath has detected it.

~# multipath -ll /dev/sdav
2796a30585a4b6e45 dm-12 ,
size=2.2T features='0' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=0 status=active
| `- #:#:#:# sdav 66:48  active undef running

then to fix it, remove from multipath:

~# multipath -f /dev/sdav

And finally you can format it without any problem:

~# mkfs -t xfs -f -i size=2048 /dev/sdav2
meta-data=/dev/device            isize=2048   agcount=4, agsize=3277258 blks
         =                       sectsz=512   attr=2
data     =                       bsize=4096   blocks=13109032, imaxpct=25
         =                       sunit=0      swidth=0 blks
naming   =version 2              bsize=4096   ascii-ci=0
log      =internal log           bsize=4096   blocks=6400, version=2
         =                       sectsz=512   sunit=0 blks, lazy-count=1
realtime =none                   extsz=4096   blocks=0, rtextents=0